Coenzyme Q10 (structure below, wherein x=10) is an oil soluble compound that is present in virtually all eukaryotic cells. It is found primarily in the mitochondria where it plays a key role in the electron transport chain that generates energy in the form of ATP (adenosine triphosphate), the source of 95% of the energy in the human body. Coenzyme Q10, abbreviated as CoQ10 and also known as Ubiquinone, is characterized by the presence of 10 isoprene units on its side chain. Other CoQ compounds with fewer isoprene units exist, e.g., coenzyme Q1 to Q9, but are less common.
Coenzyme Q compounds, wherein x=1-10
This oil-soluble, vitamin-like substance is present in most eukaryotic cells, primarily in the mitochondria. It is a component of the electron transport chain and participates in aerobic cellular respiration, generating energy in the form of ATP. Ninety-five percent of the human body's energy is generated in this way. Therefore, those organs with the highest energy requirements—such as the heart, liver and kidney—have the highest CoQ10 concentrations. There are three redox states of coenzyme Q: fully oxidized (ubiquinone), semiquinone (ubisemiquinone), and fully reduced (ubiquinol). The capacity of this molecule to exist in a completely oxidized form and a completely reduced form enables it to perform its functions in electron transport chain and as an antioxidant respectively. In the reduced forms (ubisemiquinone and ubiquinol) one or both carbonyls (C═O) are replaced by hydroxyl (C—OH) groups.
The antioxidant nature of coenzyme Q10 (CoQ10) derives from its energy carrier function. As an energy carrier, the CoQ10 molecule is continually going through an oxidation-reduction cycle. As it accepts electrons, it becomes reduced. As it gives up electrons, it becomes oxidized. In its reduced form, the CoQ10 molecule holds electrons rather loosely, so this reduced CoQ10 molecule will quite easily give up one or both electrons and, thus, act as an antioxidant. CoQ10 inhibits lipid peroxidation by preventing the production of lipid peroxyl radicals ((LLO). Moreover, CoQH2 reduces the initial preferryl radical and singlet oxygen, with concomitant formation of ubisemiquinone and H2O2. This quenching of the initiating perferryl radicals, which prevent propagation of lipid peroxidation, protects not only lipids, but also proteins from oxidation. In addition, the reduced form of CoQ effectively regenerates vitamin E from the a-tocopheroxyl radical, thereby interfering with the propagation step. Furthermore, during oxidative stress, interaction of H2O2 with metal ions bound to DNA generates hydroxyl radicals and CoQ efficiently prevents the oxidation of bases, in particular, in mitochondrial DNA. In contrast to other antioxidants, this compound inhibits both the initiation and the propagation of lipid and protein oxidation. It also regenerates other antioxidants such as vitamin E. The circulating CoQ10 in LDL prevents oxidation of LDL, therefore, by providing its benefits in cardiovascular diseases.
CoQ10 is a powerful antioxidant that protects lipids and proteins in the body from oxidation. In its reduced form (ubiquinol) it regenerates vitamin E by reducing the α-tocopheroxyl radical. CoQ10 is added to topically applied skin care creams and lotions for its antioxidant properties and for its reputed ability to improve the appearance of fine lines and wrinkles and maintain the skin's vitality and elasticity.
Coenzyme Q10 is approved for use as an orphan product in the treatment of Huntington's disease and mitochondrial cytopathies; other uses include the treatment of congestive heart failure and athletic performance. Coenzyme Q10 also helps to maintain a healthy cardiovascular system. There is evidence of CoQ10 deficiency in heart failure. Recently, CoQ10 plasma concentrations have been demonstrated as an independent predictor of mortality in chronic heart failure, CoQ10 deficiency being detrimental to the long-term prognosis of chronic heart failure. CoQ10 is available as medicine in several European countries, but is in these countries also available as a food supplement. Oxidation of the circulating LDL is thought to play a key role in the pathogenesis of atherosclerosis, which is the underlying disorder leading to heart attack and ischemic strokes and CHD. Studies in the last decade have demonstrated that the content of Ubiquinol in human LDL affords protection against the oxidative modifications of LDL themselves, thus lowering their atherogenic potency.
Supplementation of coenzyme Q10 has been found to have a beneficial effect on the condition of some sufferers of migraine headaches. CoQ10 is also being investigated as a treatment for cancer, and as relief from cancer treatment side-effects. Another recent study shows a survival benefit after cardiac arrest if coenzyme Q10 is administered in addition to commencing active cooling of the body to 90-93 degrees Fahrenheit (32-34 degrees Celsius).
A recent (2007) meta-analysis of the clinical trials CoQ10 for hypertension reviewed all published trials of coenzyme Q10 for hypertension, and assessed overall efficacy, consistency of therapeutic action, and side-effect incidence. Coenzyme Q10 has been shown to lower systolic blood pressure by up to 17 mm Hg and diastolic blood pressure by up to 10 mm Hg without significant side-effects.
Studies also have shown that diseased gum tissue is deficient in CoQ10 compared to healthy gum tissue. Human clinical trials have shown a link between oral administration of CoQ10 and improved gingival health, immune response in gum tissues, and a reversal of the diseased gum conditions. In addition to oral supplementation, topical application of CoQ10 on gum tissues has been shown to improve periodontitis and gingivitis conditions. A 202 study in 80 Parkinson's disease patients found 1200 mg/day reduced the progression by 44%.
One major drawback to the clinical use of coenzyme Q10, especially topically for the uses described above, is the high photodegradation of coenzyme Q10 upon exposure to UV light. The absorption of ultraviolet light by coenzyme Q10 causes reactions that result in the formation of photoproducts and the reduction of a significant amount of the coenzyme Q10 compound. These photoreaction products are the result of UV light causing the excitation of an electron in the coenzyme Q10 molecule from an initially occupied, low energy orbital to a higher energy, previously unoccupied orbital. The energy of the absorbed photon is used to energize an electron and cause it to “jump” to a higher energy orbital, see Turro, Modern Molecular Photochemistry, 1991. Two excited electronic states derive from the electronic orbital configuration produced by UV light absorption. In one state, the electron spins are paired (antiparallel) and in the other state the electron spins are unpaired (parallel). The state with paired spins has no resultant spin magnetic moment, but the state with unpaired spins possesses a net spin magnetic moment. A state with paired spins remains a single state in the presence of a magnetic field, and is termed a singlet state. A state with unpaired spins interacts with a magnetic field and splits into three quantized states, and is termed a triplet state.
In the electronically excited state, the coenzyme Q10 molecule is prone to degrade via a number of known pathways and, reacts to form photoproducts, thereby reducing the remaining therapeutic concentration of coenzyme Q10. To photostabilize the coenzyme Q10 compound, it must be returned to the ground state before it undergoes the photochemical reactions that forms these photoproducts and, thereby, reduces the concentration of coenzyme Q10, thereby reducing its effectiveness for its intended use.
This photoinstability of coenzyme Q10 compounds is highly problematic when developing and using topical coenzyme Q10 compounds and orally ingested coenzyme Q10 compound-containing compositions for clinical purposes. To reduce the amount of photodegradation that occurs in coenzyme Q10 compound-containing products, manufacture of the coenzyme Q10 product must occur in the dark or under special lighting conditions, and the packaging of the coenzyme Q10 product must be light fast. Even if coenzyme Q10 compound-containing products are manufactured in the dark and stored in a light fast package, they quickly degrade upon application to the skin, rendering the coenzyme Q10 product much less effective.